Intervertebral disc prosthesis and instrumentation for insertion of the prosthesis between the vertebrae

ABSTRACT

The present invention relates to an intervertebral disc prosthesis and insertion instrumentation, the prosthesis comprising at least first and second osseous anchoring means, the first osseous anchoring means disposed proximal to the periphery of the plate on which it is situated and the second osseous anchoring means being offset along the antero-posterior axis, the second osseous anchoring means comprising a basal portion and a sharp-edged portion of width narrower than the basal portion. The instrumentation comprises a rod fitted with at least two feet forming a clip and sliding in a tube, sliding the rod in the tube, in the direction of the manipulation end, causing closing of the clip by contact between the exterior of the feet and a truncated portion of the tube and sliding the rod in the tube, in the direction of the prehension end, causing opening of the clip by contact between an axis and the interior of the feet of the rod.

CROSS REFERENCE TO RELATED APPLICATIONS

This application continuation of U.S. patent application Ser. No.13/620,797 filed Sep. 15, 2012, and issuing as U.S. Pat. No. 8,771,284on Jul. 8, 2014, which is a divisional of U.S. patent application Ser.No. 11/362,253 filed Feb. 24, 2006, which claims priority under 35U.S.C. 119 to French Patent Application No. 05 12133, filed in FRANCE onNov. 30, 2005.

BACKGROUND OF THE INVENTION

The present invention concerns an intervertebral disc prosthesis,intended to be substituted for fibro-cartilaginous discs ensuringconnection between the vertebrae of the spinal column.

Various types of intervertebral disc prostheses are known in the priorart. Numerous prostheses, such as for example in the patent applicationsWO 02 089 701 and WO 2004/041129, are constituted by a lower plate andan upper plate forming a sort of cage articulated about a central core.Other prostheses such as those described in the U.S. Pat. No. 5,676,701and in the patent application WO 03/059212 A1, for example, compriseonly a lower plate and an upper plate articulated to one another bymeans of an articulation surface. The advantage of these two types ofarticulated prostheses is that they offer freedom of movement for thepatient wearing the prosthesis, by enabling inclination and/or rotationof one of the plates relative to the other. The additional advantage ofprostheses comprising a central core, mobile between the plates, is thatthey allow spontaneous positioning of the core in the ideal position toabsorb the constraints imposed on the prosthesis. Some of the prostheseswhereof the central core is mobile between the plates comprisecooperation means present on the core and on at least one of the platesto limit displacement of the core. In these prostheses described in theprior art, osseous anchoring means are likewise known which fix each ofthe plates of the prosthesis in each of the vertebrae between which theprosthesis is intended to be implanted. These osseous anchoring meanscan consist of fins intended to be fixed on the plates of the prosthesisand cooperate with a groove made in the surface of the vertebral platesor in anchors intended to be planted in the vertebral body.

However, the disadvantage of these prostheses is that they are not easyto insert between the vertebrae, since implantation requires goodstability of the different elements of the prosthesis between oneanother. This stability is often missing in prostheses known from theprior art and the known instrumentation does not generally ensurestability of the elements of the prosthesis. In fact, the articulatedplates of the prostheses possess degrees of liberty conferring comfortto the patient, but discomfort for the surgeon who fits them. The platesrisk inclining and turning about their articulation surfaces. Thesurgeon is therefore not guaranteed that the elements are properlyaligned in the antero-posterior axis of the vertebral column.

SUMMARY

In this context, it is interesting to propose a prosthesis andassociated instrumentation enabling the prosthesis to be implantedbetween the vertebrae, while retaining the necessary alignment of thedifferent elements of the prosthesis between one another. The aim of thepresent invention therefore is to eliminate certain disadvantages of theprior art by proposing an intervertebral disc prosthesis andinstrumentation for insertion of the prosthesis between the vertebraeallowing the prosthesis to be implanted by following a defined axis.

This aim is attained by an intervertebral disc prosthesis comprising atleast two plates, so-called first and second plates, articulated betweenone another by means of a curved surface, so-called articulation, of atleast one of the plates, allowing pivoting and/or inclination of theplates relative to one another, by rotation about, respectively, an axissubstantially perpendicular to the plane of the plates and an axissubstantially in the plane of the plates, each of the plates comprisinga so-called contact surface, intended to be made solid with a vertebralplate of one of the vertebrae between which the prosthesis is intendedto be implanted, characterised in that the contact surface of at leastone of the plates comprises at least first osseous anchoring means andat least second osseous anchoring means, the first osseous anchoringmeans extending to in the vicinity of the periphery of the plate onwhich it is situated and the second osseous anchoring means being offsetaccording to the antero-posterior axis relative to the first osseousanchoring means, said second osseous anchoring means offset comprising aportion, so-called basal, solid with the plate on which it is situatedand a portion, so-called sharp-edged, of width narrower than the basalportion and forming a guide blade intended to prevent rotation of theplates of the prosthesis between one another and facilitate insertion ofthe prosthesis.

In accordance with another specific characteristic, the second platecomprises a curved articulation surface whereof at least one partcooperates with a curved articulation surface of the first plate towhich it is complementary, to allow pivoting and/or inclination of theplates relative to one another.

In accordance with another specific characteristic, the curved surfaceof the first plate is concave and the curved articulation surface of thesecond plate is convex.

In accordance with another specific characteristic, the curved surfaceof the first plate is convex and the curved articulation surface of thesecond plate is concave.

In accordance with another specific characteristic, it likewisecomprises a core comprising a plane surface and a curved articulationsurface and in that only the first plate comprises a curved articulationsurface cooperating with at least one part of the curved surface of thecore to which it is complementary, to allow pivoting and/or inclinationof the plates relative to one another, the plane surface of the corecooperating with at least one part of a plane surface of the secondplate to allow translation and/or rotation of the core relative to thesecond plate in at least one direction perpendicular to the verticalaxis of the backbone, the second plate comprising cooperation meanscomplementary to cooperation means of the core allowing at least thistranslation of the core to be limited or eliminated relative to thesecond plate.

In accordance with another specific characteristic, the curved surfaceof the first plate is concave and the curved surface of the core isconvex.

In accordance with another specific characteristic, the curved surfaceof the first plate is convex and the curved surface of the core isconcave.

In accordance with another specific characteristic, the first osseousanchoring means of the plates consist of at least one winglet located inthe vicinity of the periphery of the plate and fitted with notchesoriented so as to oppose withdrawal of the prosthesis from the discalspace.

In accordance with another specific characteristic, the notches of thefirst osseous anchoring means are at a height increasing in thepostero-anterior direction, such that the notches are at a heightgreater at the front than at the rear of the prosthesis and so that theinsertion of the prosthesis in the discal space, in the antero-posteriordirection of the vertebrae is facilitated by the notches attacking theosseous tissue not yet attacked by the preceding notches.

In accordance with another specific characteristic, at least theanterior edge of at least one of the plates of the prosthesis comprises3 support faces whereof one leading face substantially perpendicular tothe insertion axis of the prosthesis in the discal space and twoantero-lateral faces each forming, in the plane of the plate, an anglewith the anterior face and with one of the lateral edges of the plate,these 3 support faces allowing stabilising of the prosthesis during itsinsertion in the discal space by an instrument whereof at least aportion has a shape complementary to these 3 support faces.

In accordance with another specific characteristic, at least one of theplates has, at least on its posterior edge, at least one chamferfacilitating insertion of the prosthesis in the discal space.

In accordance with another specific characteristic, the second osseousanchoring means of the plates consists of at least one aileron locatedin the vicinity of an edge of the plate and oriented in the insertionaxis of the prosthesis between the vertebrae.

In accordance with another specific characteristic, the aileron has alesser height at its posterior end than at its anterior end, thisdifference in height imparting to the aileron an inclined profilefacilitating its insertion in the discal space in the antero-posteriordirection.

In accordance with another specific characteristic, at least one of theplates comprises at least one default form, such as a notch, allowingthe fitting of the end of a prehension device to the prosthesis.

In accordance with another specific characteristic, the cooperationmeans of the second plate are male means located in the vicinity of theedges of the second plate and cooperating with female means of the core.

In accordance with another specific characteristic, the male cooperationmeans of the second plate are two studs located on the two lateral edgesof the second plate and the female cooperation means of the core are tworecesses made on the lateral edges of the core.

In accordance with another specific characteristic, the dimensions ofeach male cooperation means are slightly less than those of each femalecooperation means so as to allow a slight clearance between the core andthe second plate about the middle position of the core, corresponding toa centre of articulation of the prosthesis.

In accordance with another specific characteristic, the dimensions ofeach male cooperation means are substantially the same as those of eachfemale cooperation means, so as to prevent any clearance between thecore and the second plate and block the core in its middle positioncorresponding to a centre of articulation of the prosthesis.

In accordance with another specific characteristic, the cooperationmeans of the second plate are female means located in the vicinity ofthe edges of the second plate and cooperating with male means of thecore.

In accordance with another specific characteristic, the dimensions ofeach male cooperation means are slightly less than those of each femalecooperation means so as to allow slight clearance between the core andthe second plate, about the middle position of the core, correspondingto a centre of articulation of the prosthesis.

In accordance with another specific characteristic, the dimensions ofeach male cooperation means are substantially the same as those of eachfemale cooperation means so as to prevent any clearance between the coreand the second plate and block the core at its middle position,corresponding to a centre of articulation of the prosthesis.

In accordance with another specific characteristic, the male cooperationmeans of the core are two studs located on the two lateral edges of thecore and the female cooperation means of the second plate are four wallslocated, two by two, on each of the two lateral edges of the secondplate.

In accordance with another specific characteristic, the femalecooperation means of the second plate comprise a portion curved in tothe centre of the plate and partially covering the male cooperationmeans of the core so as to prevent lifting of the core.

In accordance with another specific characteristic, the plane meansrepresenting the contact surfaces of the plates are substantiallyparallel or form an acute angle, the inclination obtained by such anangle allowing the overall form of the prosthesis to adapt to theanatomy of the backbone or optionally correct faults in inclination ofthe vertebrae of the patient for whom the prosthesis is intended.

In accordance with another specific characteristic, the same plates canbe assembled with cores of different thicknesses and/or sizes and/orforms.

Another aim of the present invention is to eliminate certaindisadvantages of the prior art by proposing instrumentation forinsertion of an intervertebral disc prosthesis between the vertebraeallowing stability of the different elements of the prosthesis to bemaintained between one another over the course of insertion of thelatter between the vertebrae.

This aim is attained by insertion instrumentation of an intervertebraldisc prosthesis between the vertebrae, comprising at least oneprehension device for the prosthesis comprising a so-called manipulationend and a so-called prehension end, the prehension device beingcharacterised in that it comprises a rod fitted, at the prehension end,with at least one axis of rotation on which are mounted at least twofeet free in rotation about this axis, the ensemble of the rod and feetforming a clip mounted slidably in a hollow tube whereof the prehensionend has an internal profile in a truncated form and comprises an axisperpendicular to the plane of the two feet of the clip, the ensembleformed by the two feet having a width, in the plane of the opening ofthe clip, greater than the width of the rod, the sliding of the rod inthe tube, in the direction of the manipulation end, therefore causingclosing of the clip by contact between the exterior of the feet and thetruncated portion of the tube, the sliding of the rod in the tube, inthe direction of the prehension end, causing opening of the clip bycontact between the axis of the tube and the interior of the feet of therod.

In accordance with another specific characteristic, the rod is fittedwith a grip at the manipulation end, so as to allow the user to have therod slide in the tube.

In accordance with another specific characteristic, the tube is fittedwith a ring mobile in rotation relative to the tube and comprising athread complementary to at least one threaded portion of the rod, therelative position of the thread of the ring and of the threading of therod allowing blockage of the rod in the tube at least in the positionwhere the clip is closed.

In accordance with another specific characteristic, the ends of thefeet, at the level of the prehension end, each have at least one contactsurface with at least an edge of an element of the prosthesis, impartingto the clip a profile adapted to the form of the prosthesis to beimplanted.

In accordance with another specific characteristic, the profile adaptedto the form of the prosthesis to be implanted consists of at least onecontact surface with the leading edge of the prosthesis, at least onecontact surface with the leading edge of a central core of theprosthesis and at least one contact surface with elements located on thelateral edges of the prosthesis.

In accordance with another specific characteristic, at least one contactsurface with elements located on the lateral edges of the prosthesisconsists of prehension means of cooperation means between the core and aplate of the prosthesis.

In accordance with another specific characteristic, at least one contactsurface with elements located on the lateral edges of the prosthesisconsists of cooperation means with a default form of at least one of theplates of the prosthesis.

In accordance with another specific characteristic, the profile adaptedto the form of the prosthesis to be implanted consists of at least thecontact surface with the leading edge of the prosthesis comprising 3support faces complementary to 3 support faces present at least on theleading edge of at least one of the plates of the prosthesis, these 3support faces comprising a leading face substantially perpendicular tothe insertion axis of the prosthesis in the discal space and twoantero-lateral faces each forming, in the plane of the plate, an anglewith the leading face and with one of the lateral edges of the plate,the cooperation between this instrumentation profile and these 3 facesof the prosthesis allowing the latter to be stabilised during itsinsertion in the discal space.

BRIEF DESCRIPTION OF THE DRAWINGS

Other specific characteristics and advantages of the present inventionwill emerge more clearly from reading the description hereinbelow, givenin reference to the attached diagrams, in which:

FIGS. 1A and 1B illustrate plan views in perspectives and, respectively,rear views and front views, of an intervertebral disc prosthesisaccording to an embodiment of the invention,

FIGS. 2A and 2B illustrate, respectively, a profile view and a rear viewof an intervertebral disc prosthesis according to an embodiment of theinvention,

FIGS. 3A, 3B and 3C illustrate, respectively, a plan view, a rear viewand a profile view of a first plate of an intervertebral disc prosthesisaccording to an embodiment of the invention,

FIGS. 4A, 4B and 4C illustrate, respectively, a plan view, a rear viewand a profile view of a second plate of an intervertebral discprosthesis according to an embodiment of the invention,

FIGS. 5A, 5B illustrate, respectively, a profile view with a cuttingplane of FIG. 5C and a sectional view according to this plane, of aprehension device of a prosthesis according to an embodiment of theinvention when the device is in the open position and does not lock inthe prosthesis, FIGS. 5C and 5D representing a detail, respectively ofthe part 5C enclosed in FIG. 5B and of the part 5D enclosed in FIG. 5C,

FIGS. 6A, 6B illustrate, respectively, a profile view with a cuttingplane of FIG. 6B and a sectional view according to this plane, of aprehension device of a prosthesis according to an embodiment of theinvention when the device is in the closed position and locks in theprosthesis, FIGS. 6C and 6D representing a detail, respectively of theenclosed part 6C in FIG. 6B and of the enclosed part 6D in FIG. 6C.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention relates to an intervertebral disc prosthesiscomprising at least osseous anchoring means (41) forming a guide bladeintended to prevent rotation of the plates of the prosthesis between oneanother and facilitate insertion of the prosthesis. More precisely, theprosthesis comprises at least first osseous anchoring means (42) and atleast second osseous anchoring means (41), the first osseous anchoringmeans (42) extending to near the periphery of the plate on which it issituated and the second osseous anchoring means (41) being offsetaccording to the antero-posterior axis relative to the first osseousanchoring means (42). The second offset osseous anchoring means (41)comprise a portion, so-called basal, solid with the plate on which it issituated and a portion, so-called sharp-edged, of width narrower thanthe basal portion. This sharp-edged portion forms a sort of bladeintended to score the surfaces of the vertebral plates with which itcomes into contact during implantation of the prosthesis and this bladethen naturally forms a guide rail in the vertebra, thus preventing anydisplacement of the elements of the prosthesis between one another. Inthe various embodiments described hereinbelow, the prosthesis comprisesat least two plates (1 and 2), so-called first (1) and second (2)plates, articulated between one another by means of a curved surface,so-called articulation surface, of at least one of the plates. Thiscurved articulation surface allows pivoting of the plates (1, 2)relative to one another, by rotation about an axis substantiallyperpendicular to the plane of the plates and/or inclination of theplates (1, 2) relative to one another, by rotation about an axissubstantially in the plane of the plates (1, 2). Each of the plates (1,2) comprises a so-called contact surface intended to be made solid witha vertebral plate of one of the vertebrae between which the prosthesisis intended to be implanted. As is particularly evident in theembodiment illustrated in FIGS. 1A to 3C, the contact surface of thefirst plate (1) comprises a bulged portion (14) matching the form of thesurface of the lower plate of a vertebra. The prostheses according tothe present invention could comprise only two plates articulated betweenone another by means of a curved surface (not illustrated) or two plates(1, 2) articulated between one another by means of a central mobile core(3) having a curved surface cooperating with at least one part of acurved surface of one of the plates and a plane surface cooperating withat least one part of a plane surface of the other plate, as shown inFIGS. 1A to 2B.

In this illustrated embodiment, the first plate (1) comprises a curvedarticulation surface and this surface cooperates with at least one partof the curved surface of the core (3) to which it is complementary, toallow pivoting and/or inclination of the plates (1, 2) relative to oneanother. The plane surface of the core (3) cooperates with at least onepart of a plane surface of the second plate (2) to allow translation ofthe core (3) relative to the second plate (2) in at least one directionperpendicular to the vertical axis of the spinal column and/or rotationof the core (3) relative to the second plate (2) by rotation about anaxis substantially perpendicular to the plane of these plane surfaces.In the embodiments illustrated in the figures, the curved surface of thefirst plate (1) is concave and the curved surface of the core (3) isconvex, but it could eventuate that the curved surface of the firstplate (1) is convex and the curved surface of the core (3) is concave.

The second plate (2) comprises cooperation means (22) complementary tocooperation means (32) of the core (3) so as to limit or cancel at leastthis translation of the core (3) relative to the second plate (2). Inthe embodiments illustrated in the figures, the cooperation means (22)of the second plate (2) are male means located in the vicinity of theedges of the second plate (2) and cooperating with female means (32) ofthe core (3). In the embodiments illustrated in the figures, these malecooperation means (22) of the second plate (2) are two studs located onthe two lateral edges of the second plate (2) and the female cooperationmeans (32) of the core (3) are two recesses made on the lateral edges ofthe core (3). In other possible embodiments not illustrated here, thesecooperation means (32) of the core (3) can be male means consisting, forexample, of two studs located on the two lateral edges of the core (3)and the cooperation means (22) of the second plate (2) can thus befemale means consisting, for example, of four walls located, two by two,on each of the two lateral edges of the second plate (2). In these twoembodiments, the cooperation means (22) of the second plate (2) cancomprise a portion curved in towards the centre of the plate (2) andpartially covering the cooperation means (32) of the core (3) so as toprevent lifting of the core (3). In an embodiment according to thepresent invention the dimensions of each male cooperation means (32, 22)could be slightly less than those of each female cooperation means (22,32) so as to allow slight clearance between the core (3) and the secondplate (2) about the middle position of the core (3) relative to theplates (1, 2), this middle position corresponding to a centre ofarticulation of the prosthesis. In another embodiment, the dimensions ofeach male cooperation means (32, 22) could be substantially identical tothose of each female cooperation means (22, 32) so as to prevent anyclearance between the core (3) and the second plate (2) and block thecore (3) in its middle position corresponding to the centre ofarticulation. It can be interesting that the prosthesis according to thepresent invention can correct faults in inclination of the vertebraebetween which it is intended to be implanted. In accordance with thedesired result, this centre of articulation could have been provided tobe at the centre of the prosthesis or be offset in at least onedirection perpendicular to the axis of the spinal column. Similarly, theplanes means representing the contact surfaces (14) of the plates (1, 2)could therefore be substantially parallel or form an acute angle. Theinclination obtained by such an angle will allow the overall form of theprosthesis to adapt to the anatomy of the spinal column or optionallycorrect faults in inclination of the vertebrae of the patient for whomthe prosthesis is intended. The same plates (1, 2) can be assembled withcore (3) of different thicknesses and/or sizes and/or forms.

The prosthesis according to the present invention comprises osseousanchoring means ensuring good stability of the elements of theprosthesis between one another during implantation of the prosthesisbetween the vertebrae. For this, the prosthesis according to the presentinvention comprises at least first osseous anchoring means (42) and atleast second osseous anchoring means (41). The first osseous anchoringmeans (42) extend to near the periphery of the plate on which it issituated and the second osseous anchoring means (41) is offset accordingto the antero-posterior axis relative to the first osseous anchoringmeans (42). Therefore, the first osseous anchoring means (42) couldconsist, in an embodiment not illustrated here, of a winglet orientedperpendicularly to the antero-posterior axis of the spinal column andlocated near the leading edge or posterior edge of the plate on whichthey are located. The second osseous anchoring means (41) will thus belocated in the vicinity of the edge, respectively, trailing or leading.In the embodiment illustrated on FIGS. 1A to 4C, the first osseousanchoring means (42) consist of two winglets oriented as per theantero-posterior axis of the spinal column and located in the vicinityof the lateral edges of the plate on which they are found. These lateralwinglets could have a length less than that of the plate and the secondosseous anchoring means (41) could then be located in the vicinity ofone of the trailing or leading edges of the plate. In these twoembodiments, each of the winglets could be fitted with notches orientedso as to oppose withdrawal of the prosthesis from the discal space. In avariant embodiment, the notches of the first osseous anchoring means(42) are at a height increasing in the postero-anterior direction, as isparticularly evident in FIG. 4C. More precisely, the notches are at agreater height at the front than at the rear of the prosthesis. Thus,during insertion, in the discal space, of the prosthesis in theantero-posterior direction of the vertebrae, each notch of the wingletsattacks the osseous tissue not yet attacked by the preceding notch,thereby facilitating the insertion of the prosthesis in the discalspace. The second offset osseous anchoring means (41) comprise aportion, so-called basal, solid with the plate on which it is situatedand a portion, so-called sharp-edged, of a width narrower than the basalportion and forming a guide blade intended to prevent rotation of theplates of the prosthesis between one another and facilitate insertion ofthe prosthesis. This sharp-edged portion could be obtained, for example,due to at least one chamfer made on at least one of the lateral surfacesof the second osseous anchoring means (41). This second osseousanchoring means (41) could therefore consist, for example, of at leastone aileron (41) or fin located in the vicinity of an edge of the plateand oriented in the insertion axis of the prosthesis between thevertebrae. Of course, two ailerons or fins could be provided to furtherstill stabilise the prosthesis, even though the role of the aileron ismore important on the posterior edge of the prosthesis, because theprosthesis is generally implanted along an antero-posterior pathwaythrough the discal space between two adjacent vertebrae of the spinalcolumn and this posterior edge is thus the first to be inserted in thediscal space. In a variant embodiment, the aileron or fin could have aheight less important at its posterior end than at its anterior end.Just as for the increasing height of the notches of the winglets, thisdifference in height of the aileron (41) gives it an inclined profilefacilitating its insertion in the discal space in the antero-posteriordirection. In addition, at least one of the plates (1, 2) of theprosthesis according to the present invention could, in an embodiment,comprise, at least on its trailing edge, at least one chamferfacilitating insertion of the prosthesis in the discal space.

In an embodiment of the invention, at least the leading edge of at leastone of the plates (1, 2) of the prosthesis could comprise 3 supportfaces, as is particularly evident in FIGS. 3A and 4A. These 3 facesconsist of a leading face substantially perpendicular to the insertionaxis of the prosthesis in the discal space and two antero-lateral faceseach forming, in the plane of the plate, an angle with the leading faceand with one of the lateral edges of the plate. Instead of presenting arounded leading face, the prosthesis equipped with these 3 support facesis easy to stabilise during its insertion in the discal space, forexample by means of an instrument whereof at least one portion has aform complementary to these 3 support faces. As is particularly evidentin FIGS. 1A, 1B, 2A, 3A and 3C, at least one of the plates (1, 2) couldcomprise at least a default form (43), such as a notch, allowing thefitting of the end of a prehension device (5) of the prosthesis.

The invention further relates to instrumentation allowing insertion ofthe prosthesis between the vertebrae, ensuring good stability of thedifferent elements of the prosthesis between one another duringimplantation. Such instrumentation according to the present inventioncomprises at least a prehension device (5) of the prosthesis, comprisinga so-called manipulation end and a so-called prehension end. Thisprehension device (5) comprises a rod (50) fitted, at the prehensionend, with at least an axis of rotation (501) on which are mounted atleast two feet (500) free in rotation about this axis (501). Theensemble of the rod (50) and feet (500) forms a clip mounted slidably ina hollow tube (55) whereof the prehension end has an internal profile oftruncated shape. The ensemble formed by the two feet (500) have a width,in the plane of the opening of the clip, greater than the width of therod (50), so as to cooperate with the truncated portion of the hollowtube (55). The tube (55) comprises an axis (550) perpendicular to theplane of the two feet (500) of the clip and located between the twofeet, so as to cooperate with the latter. The sliding of the rod (50) inthe tube (55), in the direction of the manipulation end, thereforecauses closing of the clip by contact between the exterior of the feet(500) and the truncated portion of the tube (55), while the sliding ofthe rod (50) in the tube (55), in the direction of the prehension end,causes opening of the clip by contact between the axis (550) of the tube(55) and the interior of the feet (500) of the rod (50). The rod (50)could be fitted with a grip (56) at the manipulation end, so as to allowthe user to have the rod (50) slide in the tube (55). Also, this gripcould be utilised to force insertion of the prosthesis in the discalspace, for example, by striking on the grip by means of a tool such as ahammer, for example. The tube (55) could, in an embodiment of theinvention, be fitted with a ring (57) mobile in rotation relative to thetube (55) and comprising a thread complementary to at least one threadedportion (58) of the rod (50). The relative position of the thread of thering (57) and of the threading (58) of the rod (50) shall allow blockageof the rod (50) in the tube (55) at least in the position where the clipis closed. So, use of the prehension device (5) will help secure theclip on the prosthesis, for example while the surgeon strikes on thegrip to insert the prosthesis in the discal space.

In the embodiment illustrated on the figures, the ends of the feet(500), at the level of the prehension end, each have at least onecontact surface (51, 52, 53) with at least an edge of an element of theprosthesis, imparting to the clip a profile adapted to the form of theprosthesis to be implanted. This profile adapted to the form of theprosthesis to be implanted could consist of at least one contact surface(51) with the leading edge of the prosthesis, at least one contactsurface (53) with the leading edge of a central core of the prosthesisand at least one contact surface (52) with elements located on thelateral edges of the prosthesis. In the case where the prosthesiscomprises a central core fitted with cooperation means cooperating withcooperation means of at least one of the plates, the contact surface(52) with elements located on the lateral edges of the prosthesis couldthus consist of prehension means of at least one of the cooperationmeans between the core (3) and a plate (1, 2) of the prosthesis. In thesame way, in the case where the prosthesis comprises a plate having adefault form (43), such as a notch, the contact surface (52) withelements located on the lateral edges of the prosthesis could consist ofcooperation means with this default form (43). Also, the instrumentationaccording to the invention could be provided to cooperate perfectly withthe different variant embodiments of the prosthesis according to thepresent invention and comprise a profile even more adapted to the formof the prosthesis. In particular, the contact surface (51) with theleading edge of the prosthesis, as well as optionally other surfaces,could comprise 3 support faces complementary to 3 support faces presentat least on the leading edge of at least one of the plates (1, 2) of theprosthesis. These 3 support faces placed in complementary fashion tothose of the prosthesis, then comprise a leading face substantiallyperpendicular to the insertion axis of the prosthesis in the discalspace and two antero-lateral faces each forming, in the plane of theplate, an angle with the leading face and with one of the lateral edgesof the plate. Cooperation between this instrumentation profile and these3 faces of the prosthesis will help stabilise the latter during itsinsertion in the discal space, for example by preventing its rotation.

It must be evident for those skilled in the art that the presentinvention allows embodiments in numerous other specific forms withoutdeparting from the field of application of the invention as claimed.Consequently, the present embodiments must be considered by way ofillustration, though they can be modified in the field defined by thereach of the attached claims, and the invention does not have to belimited to the details specified hereinabove.

The invention claimed is:
 1. A combination comprising: an intervertebraldisc prosthesis for implantation between vertebrae of a spinal columnalong an insertion axis, the prosthesis comprising: a first plate and asecond plate, each comprising leading and trailing edges and two lateraledges, with the first plate having a curved plate articulation surfaceand the second plate having a planar plate translation surface; a corehaving a curved core articulation surface and a planar core translationsurface, the core configured for at least a portion of the curved corearticulation surface to cooperate with at least a portion of the curvedplate articulation surface to allow pivoting or inclination of the firstplate and the second plate relative to one another, and at least aportion of the planar core translation surface to cooperate with atleast a portion of the planar plate translation surface to allowtranslation or rotation of the core relative to the second plate in atleast one direction; and at least two recesses disposed along oppositeedges of the core, each recess configured to receive one of at least twostuds disposed on the first or second plate proximal to lateral edges ofthe plate and configured to limit translation of the core with respectto the second plate, with each stud configured to extend outside theedge of the core to allow the studs to be grasped by an insertioninstrument to hold the plate during insertion of the prosthesis; and aninsertion instrument for inserting the intervertebral disc prosthesisbetween vertebrae of a spinal column along an insertion axis, theinstrument comprising feet rotatable about an axis of rotation, the feetcollectively forming a clip for grasping the intervertebral discprosthesis, the clip having a pair of recesses each configured toenvelope an end of one of the studs and grasp the stud with the clipconfigured in a closed configuration.
 2. The combination of claim 1 inwhich the trailing edges of the plates and a trailing edge of the coreeach has a support profile, and the instrument comprises complementarysupport profiles configured to support the intervertebral prosthesis andmaintain orientation of the intervertebral prosthesis along theinsertion axis during implantation of the intervertebral prosthesis.